If this behavior occurs in other environments, it might be best to get this behavior evaluated by an MD. It could be a form of autism or a developmental disorder.
yes if left alone, and he thinks nobody is looking, he will do it for an hour or so then just stop i think it must be some sort of soothing . it is strange that he will do it in preference to other normal activity for a child of his age although he is normal in many other ways
like above
but i feel possible masturbating learning that feels good lots of others
im adhd and as long as i can remember embarrassing
i masturbated in one way or anothe all the time some is normal male discovery
but its hard to know the line if its all the time consult docs counselors etc for ideas
its really his parents his home life discipline or lack of
my wifes work her old boss her kids heard to much of the sick crap in the house
and always tried to reenact on playground we wont go into the nasty details
start by seeing if you can find out what goes on in the other house
some just laugh o there young its funny and encourage this to get worse
good luck
Ya, does seem odd. Does he really do this for hours at a time? If so may be a form of self soothing - not mastrabating. Does he seem sensitive to clothing , or food, or sound, etc
It seems a bit odd to me. Have you spoken to his other parent about this behavior? Does it occur there as well?